Sadly, NPH won't actually be playing Dr. Horrible, since that would probably fracture the space-time continuum. Instead, he'll be playing the Music Meister, an amalgam of various DC Comics villains, who uses his ability to create music to dominate the world. Or something. He's a former band camp nerd who's become a megalomaniac. Mostly, the episode's plot is "just an excuse to have everyone sing," says producer James Tucker. Oh, like the Buffy musical episode then?